Mining Steem on a Pi 3 is pretty much impossible too... A Pi 3 only has a 4 core processor that's clocked around 1Ghz and no where near enough RAM. Even with 6 Cores at 3.2 Ghz and 16 GB I was only getting roughly between 20KH/s to 21KH/s. Not to mention someone all but DDOS'd mining if you check the list. The average time to have your POW included in a block is up to like 2 weeks now. Someone either created a botnet farm or is renting some serious server time.